[Purification and characterization of lipases from wheat germ]. / Preparativnoe poluchenie i kharakteristika lipazy zarodyshei pshenitsy.

A method of isolation and purification of lipase (EC 3.1.1.3) from the germ of wheat (Triticum aestivum) is described. Electrophoretically homogeneous preparation of the enzyme (specific activity, 622.5 x x 10(-3) mumol/min per mg protein) was obtained after purification in 61 times. The molecular weight of the enzyme, determined by gel chromatography, was 143 +/- 2 kDa. The optimal conditions for the enzyme were 37 degrees and pH 8.0. Homogeneous preparation of the lipase exhibited high thermal stability: over 20% of original activity was retained after incubation of the preparation at high temperatures (60-90 degrees) for 1 h at pH 8.0.

[Effect of gamma-aminobutyric shunt metabolites on NAD-, NADP-isocitrate dehydrogenases, and aconitate hydratase activities in higher plants]. / Vliianie metabolitov shunta gamma-aminomaslianoi kisloty na aktivnost' NAD- i NADF-isotsitratdegidrogenaz i akonitatgidratazy vysshikh rastenii.

We studied the influence of metabolites of gamma-aminobutyric shunt of the tricarboxylic acid cycle on the activities of aconitate hydratase (EC.4.2.1.3) as well as NAD- and NADP-specific isocitrate dehydrogenases (EC.1.1.1.41 and EC.1.1.1.42, respectively) using purified enzyme preparations from pea leaves (Pisum sativum L.) and maize scutellum (Zea mays L.). gamma-Aminobutyric acid and succinate proved to have no significant effect on these enzymes, while 0.1-0.2 mM glutamate considerably activated NADP isocitrate dehydrogenase from the both sources, particularly, at unsaturating concentration of the substrate. Succinic semialdehyde stimulated the activities of aconitate hydratase and NADP isocitrate dehydrogenase. The obtained data points to a similar pattern of the effect of intermediates of gamma-aminobutyric shunt on the studied enzymatic activities for both photosynthetic tissues (pea leaves) and those with acidifying, transport, and digestive functions (maize scutellum). However, the absence of pronounced control effects of most metabolites on the studied enzymes allows us to assign them to a relatively inert pool of metabolites.

[Identification of catalytically active groups in inulinase from Bacillus polymyxa 722]. / Identifikatsiia kataliticheski aktivnykh grupp inulinazy Bacillus polymyxa 772.

Inulinase from Bacillus polymyxa 722 hydrolyzing a polyfructosan inulin was studied. The dependence of inulinase activity on pH, measurements of pK value, calculation of ionization heat, photoinactivation with methylene blue, and inhibition with p-chloromercuribenzoate suggest that the active center of this enzyme contains imidazole and sulfhydryl groups. A possible mechanism underlying cleavage of beta-2,1-fructoside bonds in the inulin molecule with inulinase is considered.

[Biosynthesis of inulinases by Bacillus bacteria]. / Biosintez inulinaz bakteriiami roda Bacillus.

Biosynthesis of extracellular inulinase by bacteria Bacillus polymyxa 29, B. polymyxa 722, and B. subtilis 68 was studied. The optimal parameters for the producer growth were as follows: pH 7.0, 33-35 degrees C, the growth duration within 72 h. The presence of mineral reduced or of organic nitrogen was necessary for the enzyme biosynthesis. The inulinase biosynthesis was sharply activated in the presence of carbohydrates. B. polymyxa 722 and B. polymyxa 29 displayed the maximal activity on a starch-containing culture medium, the maximal activity of B. subtilis 68 was found in the presence of sucrose. Inulin did not induce the inulinase biosynthesis by the strains studied. The time course of bacteria growth and of the enzyme biosynthesis was studied.

[Identification of catalytically active groups of lipoxygenase from wheat germ]. / Identifikatsiia kataliticheski aktivnykh grupp lipoksigenazy zarodyshei semian pshenitsy.

Catalytically active groups of lipoxygenase in wheat germs have been identified. Blocking of catalytically active groups by specific reagents, dependence of the enzyme activity on pH, enthalpy of ionization of pK1 and pK2, the enzyme photoinactivation allowed to make a conclusion that imidasole and hydroxyl groups take part in lipoxygenase catalytic cycle.

[Immobilization of glucoamylase from Aspergillus awamori 466, and properties of the preparation]. / Immobilizatsiia glukoamilazy iz Aspergillus awamori 466, nekotorye svo stva preparata.

Glucoamylase from Aspergillus awamori 466 was immobilized on various supports. The enzyme sorption depends on its amount, the type of support, and immobilization conditions. The kinetics of acidic inactivation of the native and immobilized enzyme was studied. The immobilized enzyme was more resistant to temperature and pH. The mechanism of the enzyme binding to the support was investigated by IR spectroscopy.

Identification of catalytically active groups of Penicillium canescens F-436 beta-galactosidase.

The functional groups of Penicillium canescens F-436 beta-galactosidase have been identified. The pK values and heats of ionization of these groups and photoinactivation of the enzyme with methylene blue indicate that the active site contains carboxyl and imidazole groups. A mechanism for the participation of these groups in the cleavage of the glycoside bond in lactose is proposed.

Fumaric acid is a competitive inhibitor of wheat germ lipoxygenase.

Fumaric acid is shown to be a competitive inhibitor of wheat germ lipoxygenase.

Study on splitting of sucrose glycoside bonds by beta-fructosidase of Aspergillus niger VKM F-801.

Functional groups of beta-fructosidase of Aspergillus niger VKM F-801 were identified. Based on the pH dependence of the enzyme, the calculated heat of ionization, the photoinactivation of the enzyme in the presence of methylene blue photosensitizer, and also the enzyme inactivation by diethyl pyrocarbonate, the catalytic center of the beta-fructosidase was found to include carboxyl and imidazole groups of amino acid residues. The glycoside bond in the sucrose molecule is apparently cleaved by the catalytically active carboxylate--imidazole pair.

[Regulation of the biosynthesis of endo-1,4-beta-glucanase, eco-1,4-beta-glucosidase and cellobiase in Aspergillus terreus]. / Reguliatsiia biosinteza éndo-1,4-beta-gliukanazy, ékzo-1,4-beta-gliukozidazy i tsellobiazy u Aspergillus terreus.

This work was aimed at studying how the biosynthesis of endo-1,4-beta-glucanase, exo-1,4-beta-glucosidase and cellobiase, components of the cellulase complex was regulated in an Aspergillus terreus strain isolated from soil. The biosynthesis of endoglucanase and cellobiase was suppressed by readily metabolizable substrates and stimulated in the course of growth on lactose and celluloses. The activity of exoglucosidase was found in the medium only when the strain was grown on celluloses. Catabolite repression was assumed to be an important mechanism regulating the biosynthesis of cellulases by the culture. The derepression was insufficient however to stimulate the biosynthesis of all the three enzymes. Besides lactose and celluloses, cellobiose taken at a low concentration also exhibited the inducing effect. Under the conditions of derepression and induction, the activity of the three enzymes, the components of the complex, increases in the growth medium in parallel to the cultural growth. The synthesis and excretion of endoglucanase and exoglucosidase coincided in time whereas a considerable portion of the cellobiase activity was displayed by the cells. The results suggest that the regulation of endoglucanase, exoglucosidase and cellobiase biosynthesis are coordinated at the level of catabolite repression and induction.

[Mechanism of amylase action on glucoside starch bonds]. / O mekhanieme deistviia amilaz na liukozidnye sviazi krakhmala

Functional groups of glucoamylase and alpha-amylase from Asp. awamori, alpha-amylase from Asp. oryzae and alpha- and beta-amylases from barley malt are identified. Kinetic curves of the activity dependency on pH, values of ionization heats and photooxidative inactivation draw to the conclusion that carboxyl-imidazole system enters into the active site of the enzymes. A hypothetic mechanism of hydrolysis of alpha-1,4-glucoside bond in starch molecule by alpha- and beta-amylases and of alpha-1,4- and alpha-1,6-glucoside bonds by glucoamylase is given. A theory of induced correspondence of enzyme and substrate satisfactorily explains the specificity of the enzyme action and the cause of complete starch convertion into glucose under glucoamylase action and of terminal starch hydrolysis by alpha- and beta-amylases.

[Some properties of proteases of the mould Mucor pusillus-917]. / Izuchenie nekotorykh svoistv proteaz pleshevogo griba mucor pusillus-917

The proteolytic preparation of Mucor pusillus-917 has been obtained. The preparation produces an effective hydrolytic influence on milk casein. Thermal and acid inactivation of the proteolytic complex is the reaction of the first order. The activity-pH curves, calculations of ionization heat, inactivation of proteases by photooxidation and monoiodoacetic acid suggest that imidazole, carboxyl and sulphydryl groups of proteases are involved in the clotting and hydrolysis of milk.